The following relates generally to wireless communication, and more specifically to beam refinement techniques in millimeter wave (mmW) systems.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as a Long Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
In a mmW system, a base station and a UE may communicate via one or more directional beams. A transmitter (e.g. a base station) may engage in a beam sweeping procedure to establish an active beam pair with a receiver (e.g., a UE). An active beam pair may include an active transmit beam of the transmitter and a corresponding active receive beam of the receiver. The transmit beams and the receive beams in an active beam pair may be refined through, for example, beam refinement procedures. However, such beam refinement procedures may require multiple transmissions that each include multiple training symbols. Thus, the UE may remain in an awake mode expending power receiving and/or transmitting the multiple beam refinement transmissions, and the base station and UE may utilize resources during the refinement process. Furthermore, in some cases shared or unlicensed spectrum may be used for mmW transmissions, and access to such spectrum by a UE and transmitter may be subject to contention procedures (e.g., listen before talk (LBT) procedures), which can result in additional time for beam sweeping and refinement. Techniques that may provide more efficient beam refinement may be desirable to help enhance network efficiency.